After hours of abuse and frustration about passing inspection due to bumper sizing, rookie team 4276 finally passes inspection in the afternoon on practice day (San Diego). Thank you to this particular inspector for being so patient with our team!!
For rookies, passing inspection can almost be considered a a rite of passage for joining FRC. Just thought I’d share a funny video of the team as the inspector was approaching the robot with the “passed inspection” sticker:
Just another one of those funny FRC moments. But a word of caution for upcoming weeks – check your bumpers and bring spare material to rebuild if necessary! According to one inspector, as many as 17 teams in San Diego had bumper issues.
We sized the bumpers and ball collection opening such that the bumpers themselves were over 8 inches long with bumper overlap, but the frame perimeter at that location was only 6 inches. We actually had to extend the frame itself 2 more inches inward on each side and the bumper along with it.
Also, numbering was “too wide”. After repainting the numbering, we also were informed those new front bumpers were too loose on the chassis, so we had to change out the attachment method to the chassis.
I don’t understand what’s wrong with the first part. Bumpers have to be at least 8in, so you guys met that, but had to make it larger?
Also the numbering has to be at least 3/4in but no max limit, wonder why they called you on that.
I’m worried about R33, there’s a picture in there that says that the 10in gap is okay, but the rule says it has to be 8in. It’s an issue for us, because there’s a section where we have to have the bumper attached at two points that is 10in.
popnbrown –
We thought the same thing, min 8 inch bumpers – but ready [R27] carefully:
[R27]Robots are required to use Bumpers to protect all exterior vertices of the Frame Perimeter. For adequate protection,* at least 8 in. of Bumper must be placed on each side of each exterior vertex***
The “exterior vertex” refers to the chassis (interior bumper vertex) and not the outside of the bumper. To overlap the side bumper, our front bumpers had to be min 10.75 inches.
Also, the 8 inches cited need to be fully supported by the chassis/frame perimeter. Inspectors said it was permissible to essentially extend the frame by 2 inches using a piece of stock aluminum mounted to the existing chassis and then mounting that to the bumper.
We never saw any rules defining maximum letter sizing and bumper sturdiness either.
I was an inspector at Alamo this weekend and we had a lot of issues with bumpers. Here is rule for bumper attachment.
[R27] E. must attach to the Frame Perimeter of the Robot with a rigid fastening system to form a tight, robust connection to the main structure/frame (e.g. not attached with Velcro). The attachment system must be designed to withstand vigorous game play. All removable fasteners (e.g. bolts, locking pins, pip-pins, etc.) will be considered part of the Bumpers.
At Alamo we tried to be as lenient as we could while still ensuring that robots were safe and would not damage the field or other robots. I don’t see how a number could be too wide unless it was wrapping around the side of a bumper or was not easily readable because of how it was skewed.
There were some pretty rough looking bumpers there.
Bumpers are proving tougher to make than fat first thought. I think one problem is that bumpers are an afterthought more or less and when teams realize they have to make them it’s at the last minute or at the event when they find out it’s the one thing keeping them from the field.
Any team that is particularly good at could probably have a pretty good fundraiser designing bumpers for other teams.
Look closely – the 10" OK is really talking about the 1/4" gap between bumper and frame; it has nothing to do with the max 8" of unsupported bumper. I’ve always thought that diagram was confusing.
Haha oh wow. I finally see it, the arrow was pointing to just the 1/4". Grr, that’s annoying they should have put a Not OK as well for the 10" or at least made it smaller than 10", because that part of the diagram even if it is 1/4" is not legal. They should really fix that, that’s very very misleading.
Also, seg9585, I understand what they called you guys on. I got worried that it might be an issue for us too, but I think we’re safe on the ball opening. Our side bumpers are the overlapping ones so that means the ones at the ball opening are 8in and so is the frame on that side.
Well, looks like it’s time to prep for making some more brackets. Our bumpers are pretty secure, I made sure they aren’t easily yank-able, but they do wobble a bit. Better be safe than sorry and get plan on securing them a little more.
But it is legal, the rules say that gaps between the frame and bumper and be either 8’’ wide and as deep as you want, OR 1/4" deep and as wide as you want.
[R33]Bumpers must be supported by the structure/frame of the Robot (i.e. each end of the Bumper must be rigidly attached to the Frame Perimeter, the gap between the backing material and the frame must not be greater than ¼ in. and no section of Bumper greater than 8 in. may be unsupported). See Figure 4‑7.
The wording is confusing, but what it says is a bumper 1/4" or less from the frame is “supported”, sections of bumper that are not “supported” can be no more than 8 inches in length. since the 10" gap is only 1/4" deep the bumper is considered to be “supported” across this gap, thus the 8" limit does not apply.
Let me try and explain the difference between 1/4" gap and 8" opening. We all know that no matter how hard we try, bolt heads, welds, rivets and staples will prevent the bumper from full contact with the frame. After a few years of discussion, First realized that the movement of a bumper in a full hit with a 1/4" gap behind it, is not going to compromise the bumper structure. However, a opening in the frame of greater than 8" in width and more than 1/4" behind the bumper will actually result in cracking of the 3/4" plywood or total failure of the bumper. We want you to play as much as is possible. If your bumper fails and parts of your robot get damaged or start dragging around the field, your chances of fulfilling the “play as much as possible” go down the drain.
Are teams getting dinged for bumpers (for example, let’s assume full coverage bumpers, no ‘cutout’ or “c-shaped” frame) that meet the other rules (no gap more than 1/4" deep) but are not connected at the very end? Say, securely connected to the frame 3" in from the end of the plywood?
There was a lot of discussion on here a while back about the “connected at the end” part of the rule. Is that tripping up a lot of teams?
I inspected in San Diego and I didn’t see any of that particular issue. It was mostly about the 8" minimum supported bumper from the vertex when the bot had a ball opening on the narrow end of the frame.
The bumper issues I remember were almost all this 8" problem, although we also had a few with numbers that didn’t meet the rules.
I did have one robot I inspected that had to add an attachment when they went from a 6" to a full 8" section at the side of their opening. There was only one attachment on the original segment & it was closer to the corner than it was to the opening; adding the extra 2" would have left a pretty wobbly bumper without a 2nd attachment.
